A pendant is connected to a control apparatus that controls a robot or a machine, and is used to control the robot or the like. A pendant is known that is designed to be detachable so that it can be connected to any one of a plurality of control apparatus' and so that it can be connected to or disconnected from a control apparatus as needed. In many cases, when disconnecting the pendant, the disconnection has had to be made after turning off power to the control apparatus or after putting the control apparatus in an emergency stop condition, thus taking time and labor to accomplish the task. A similar problem arises when connecting the pendant to a control apparatus.
To solve the above problem, it is known in the prior art to provide a control apparatus equipped with a “detaching” switch (for example, refer to Japanese Unexamined Patent Publication No. H5-42493). The configuration of this prior art control apparatus is shown in FIG. 1. A robot 1002 is connected to robot control apparatus 1001 equipped with an emergency stop circuit, and a first port 1003 and a second port 1004 are connected to it. The first port 1003 and the second port 1004 are identical in configuration; the first port 1003 is provided near or within the robot control apparatus 1001, while the second port 1004 is located near the robot 1002. The first port 1003 is equipped with a detaching switch SW5 and a plurality of connectors, and the second port 1004 is equipped with a detaching switch SW6 and a plurality of connectors. A pendant 1005 has a structure that is detachably connectable to the first port 1003 or a second port 1004.
In the prior art control apparatus, provisions are made so as not to activate the emergency stop function of the robot 1002 when the pendant 1005 is detached from the robot control apparatus 1001 while the detaching switch SW5 or SW6 is ON. Thus, it is claimed that the pendant 1005 can be safely detached from the robot control apparatus 1001 without causing the operation of the robot 1002 to stop.
In the prior art control apparatus, the emergency stop switch on the pendant is disabled by just operating the detaching switch. However, a situation can occur where even when power is ON to the control apparatus, the emergency stop switch on the pendant connected to the control apparatus is disabled and thus may not be operated when necessary.